This application is not based upon any pending domestic or international patent applications.
This application is not referenced in any microfiche appendix.
The present invention is a launcher for conveying a pig into a pipeline employing an upright launch barrel having a lower end in communication with the pipeline, a valve affixed to an upper end of the launch barrel, having a passageway therethrough that can be closed or open and when in the open position allows a pig to pass in an upright receiving chamber connected at its lower end to the valve in vertical alignment with the valve and launch barrel and a cover closing an upper end of the receiving chamber.
Pipeline pigs are used for several different reasons in the operation of pipelines. Pipelines can be relatively short such as for use in connecting a producing field to a refinery, but typically pipelines extend for many miles, sometimes on the earth""s surface but usually under the surface. In addition, pipelines frequently pass under bodies of water such as to cross-rivers and lakes. Much of today""s crude oil production takes place offshorexe2x80x94that is, from wells produced by use of drilling platforms. Pipelines are required to transport crude oil produced in these offshore wells to land locations where refineries are located or where shipping facilities are available.
Wells that produce gas or crude oil typically also produce water. Since water is denser than gas or hydrocarbon fluid, it tends to accumulate in low places in a pipeline and can interfere with the successful operation of the pipeline. For this reason, it is important that water be periodically removed from a pipeline which is most effectively accomplished by passing pipeline pigs through the pipeline to force the water in front of the pigs as the pigs move through the pipeline to thereby carry the water out of the pipeline and to a slop tank to be carried away for disposal.
Further, crude oil, and including water produced in conjunction with crude oil, frequently includes insoluble components such as sand, rust and so forth that tends to settle in low places in a pipeline. These insoluble contaminants must occasionally be removed from a pipeline; otherwise they can accumulate to the point where they interfere with flow of liquids or gasses through the pipeline.
Further, it is well known that the interiors of pipelines can become coated with paraffin and other contaminates and therefore it is necessary to occasionally pass pigs through a pipeline to remove contaminates that have adhered to the pipeline interior wall.
Another reason for employing pipeline pigs is to separate one component from another. If a pipeline is used to transmit more than one kind of fuel, such as gasoline and diesel fuel, a pig can be used to separate one component from another. This requirement is sometimes referred to as xe2x80x9cbatching.xe2x80x9d Instrument pigs are also frequently employed to gather information about the condition of a pipeline. These are just examples of the various reasons that the operation of pipelines require the passage of pigs through pipelines.
Various devices have been created for injecting a pig into a pipeline and for background information relating to pig launching devices, reference may be had to the following previously issued United States Patents:
The present invention satisfies the needs discussed above. The present invention provides a method and system for launching a pig into a pipeline. The system includes an upright launch barrel having a lower end in communication with the pipeline that is to receive the pig. A fully ported valve is affixed at an upper end of the launch barrel. The valve has a passageway therethrough that can be closed or opened and when in the open position is of internal diameter at least equal to the external diameter of the pig to be launched. That is, the valve is a fully ported type that when open freely allows the pig to pass downwardly therethrough.
An upright pig receiving chamber is connected at a lower end to the valve and in vertical alignment with the valvexe2x80x94that is, the receiving chamber extends vertically upwardly from an upper end of a fully ported valve. The upright receiving chamber is in coaxial vertical alignment with the valve and the launch barrel. The pig to be launched is assumed to have a diameter xe2x80x9cDxe2x80x9d and the launch barrel, the fully ported valve, and the receiving chamber all have internal diameters greater than xe2x80x9cDxe2x80x9d so that a pig to be launched freely passes downwardly through these three components without restriction and only with the affect of gravity.
A cover is removably attached to an upper end of the receiving chamber for selectively closing or opening the receiving chamber. When the cover is in open position, the upper open end of the receiving chamber is open so that a pig to be launched can be insertedxe2x80x94that is, dropped into the receiving chamber. After a pig is dropped into the receiving chamber, the cover is closed in a pressure tight arrangement.
A fluid supply conduit is connected to a fluid entry port formed in the upper portion of the launch barrel below the fully ported valve. The fluid supply conduit is controlled by a fluid control valve that may be of relatively small size compared to the fully ported valve that exists between the receiving chamber and the launch barrel.
A pressure relief port is provided in the receiving chamber and is closed by a relatively small pressure relief valve. When the pressure relief valve is opened, pressure within the receiving chamber is equalized with atmospheric pressure, meaning that it is safe to open the cover of the receiving chamber.
The launcher of this invention is used in this manner: With the fully ported valve closed, the pressure relief valve is opened to equalize pressure within the receiving chamber. When the pressure is equalized, the cover is opened exposing the open end of the vertical receiving chamber. A pipeline pig can then be placed into the receiving chamber. The receiving chamber is, as previously stated, of internal diameter greater than the external diameter of the pipeline pig so the pipeline pig will by gravity pass downwardly within the receiving chamber to the lower end and rest on the closed fully ported valve. The cover is then placed in position on the upper end of the receiving chamber and the pressure relief valve closed. The launch system then is in ready position so that when required, the pig that is within the receiving chamber can be launched when desired.
To launch the pig, the fully ported valve is fully opened allowing fluid pressure to equalize between the lower launch barrel and the upper receiving chamber. When the pressure is equalized, which occurs very quickly when the fully ported valve is open, the pig is free to pass through the fully ported valve and into the launch barrel. The pig falls to the lower end of the launch barrel where a reducing ell is encountered. The reducing ell reduces in internal diameter from that of the launch barrel to essentially that of the internal diameter of the pipeline in which the pig is to be placed. The pig therefore passes into the ell and is in a position to enter the reduced portion of the ell and ultimately into a pipeline. To move the pig from the reducing ell at the lower end of the launch barrel, fluid is directed into the upper end of the launch barrel under pressure. This high pressure fluid is supplied by a fluid supply conduit and controlled by a fluid control valve. When the fluid control valve is open, the pressure within the launch barrel builds to the point that the pig is forced from the reducing ell into the pipeline. Once in the pipeline, the pig is carried by fluid flow in the pipeline.
The pig launcher can thus be repeatedly used. It is simple in operation and requires no mechanical device to move a pig from a ready position into a pipeline.
A better understanding of the invention will be obtained from the following detailed description of a preferred embodiment, taken in conjunction with the attached drawings.